True stress:
In drawing the stress-strain diagram as shown in figure 1.13, the stress was calculated by
dividing the load P by the initial cross section of the specimen.
But it is clear that as the specimen elongates its diameter decreases and the decrease in
cross section is apparent during necking phase.
Hence, the actual stress which is obtained by dividing the load by the actual cross
sectional area in the deformed specimen is different from that of the engineering stress
that is obtained using undeformed cross sectional area.
In drawing the stress-strain diagram as shown in figure 1.13, the stress was calculated by
dividing the load P by the initial cross section of the specimen.
But it is clear that as the specimen elongates its diameter decreases and the decrease in
cross section is apparent during necking phase.
Hence, the actual stress which is obtained by dividing the load by the actual cross
sectional area in the deformed specimen is different from that of the engineering stress
that is obtained using undeformed cross sectional area.